I think the reviewer missed the point of the ending (as did I when I first watched it). SPOILER ALERT:
At the moment the screen fades to black, the Gosling character is about to tell the interviewer all about the dirty deeds the candidate has been up to, and in so doing torpedo his campaign. He didn't do it earlier because he would not be believed if he was just a "disgruntled fired employee)". As the campaign manager, he will be taken seriously.
So Clooney's character is never going to get elected.